usb: misc: onboard_usb_dev: Fix usb5744 initialization sequence

JIRA: https://issues.redhat.com/browse/RHEL-116007

commit 1143d41
Author: Jonathan Stroud <jonathan.stroud@amd.com>
Date: Fri, 16 May 2025 18:02:40 +0530

  Introduce i2c APIs to read/write for proper configuration register
  programming. It ensures that read-modify-write sequence is performed
  and reserved bit in Runtime Flags 2 register are not touched.

  Also legacy smbus block write inserted an extra count value into the
  i2c data stream which breaks the register write on the usb5744.

  Switching to new read/write i2c APIs fixes both issues.

  Fixes: 6782311 ("usb: misc: onboard_usb_dev: add Microchip usb5744 SMBus programming support")
  Cc: stable <stable@kernel.org>
  Signed-off-by: Jonathan Stroud <jonathan.stroud@amd.com>
  Co-developed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
  Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
  Link: https://lore.kernel.org/r/1747398760-284021-1-git-send-email-radhey.shyam.pandey@amd.com
  Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Desnes Nunes <desnesn@redhat.com>

Author: Desnes Nunes

drivers/usb/misc/onboard_usb_dev.c

@@ -36,9 +36,10 @@
 #define USB5744_CMD_CREG_ACCESS			0x99
 #define USB5744_CMD_CREG_ACCESS_LSB		0x37
 #define USB5744_CREG_MEM_ADDR			0x00
+#define USB5744_CREG_MEM_RD_ADDR		0x04
 #define USB5744_CREG_WRITE			0x00
-#define USB5744_CREG_RUNTIMEFLAGS2		0x41
-#define USB5744_CREG_RUNTIMEFLAGS2_LSB		0x1D
+#define USB5744_CREG_READ			0x01
+#define USB5744_CREG_RUNTIMEFLAGS2		0x411D
 #define USB5744_CREG_BYPASS_UDC_SUSPEND		BIT(3)
 
 static void onboard_dev_attach_usb_driver(struct work_struct *work);
@@ -309,32 +310,105 @@ static void onboard_dev_attach_usb_driver(struct work_struct *work)
 		pr_err("Failed to attach USB driver: %pe\n", ERR_PTR(err));
 }
 
+static int onboard_dev_5744_i2c_read_byte(struct i2c_client *client, u16 addr, u8 *data)
+{
+	struct i2c_msg msg[2];
+	u8 rd_buf[3];
+	int ret;
+
+	u8 wr_buf[7] = {0, USB5744_CREG_MEM_ADDR, 4,
+			USB5744_CREG_READ, 1,
+			addr >> 8 & 0xff,
+			addr & 0xff};
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].len = sizeof(wr_buf);
+	msg[0].buf = wr_buf;
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret < 0)
+		return ret;
+
+	wr_buf[0] = USB5744_CMD_CREG_ACCESS;
+	wr_buf[1] = USB5744_CMD_CREG_ACCESS_LSB;
+	wr_buf[2] = 0;
+	msg[0].len = 3;
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret < 0)
+		return ret;
+
+	wr_buf[0] = 0;
+	wr_buf[1] = USB5744_CREG_MEM_RD_ADDR;
+	msg[0].len = 2;
+
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].len = 2;
+	msg[1].buf = rd_buf;
+
+	ret = i2c_transfer(client->adapter, msg, 2);
+	if (ret < 0)
+		return ret;
+	*data = rd_buf[1];
+
+	return 0;
+}
+
+static int onboard_dev_5744_i2c_write_byte(struct i2c_client *client, u16 addr, u8 data)
+{
+	struct i2c_msg msg[2];
+	int ret;
+
+	u8 wr_buf[8] = {0, USB5744_CREG_MEM_ADDR, 5,
+			USB5744_CREG_WRITE, 1,
+			addr >> 8 & 0xff,
+			addr & 0xff,
+			data};
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].len = sizeof(wr_buf);
+	msg[0].buf = wr_buf;
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret < 0)
+		return ret;
+
+	msg[0].len = 3;
+	wr_buf[0] = USB5744_CMD_CREG_ACCESS;
+	wr_buf[1] = USB5744_CMD_CREG_ACCESS_LSB;
+	wr_buf[2] = 0;
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static int onboard_dev_5744_i2c_init(struct i2c_client *client)
 {
 #if IS_ENABLED(CONFIG_USB_ONBOARD_DEV_USB5744)
 	struct device *dev = &client->dev;
 	int ret;
+	u8 reg;
 
 	/*
 	 * Set BYPASS_UDC_SUSPEND bit to ensure MCU is always enabled
 	 * and ready to respond to SMBus runtime commands.
 	 * The command writes 5 bytes to memory and single data byte in
 	 * configuration register.
 	 */
-	char wr_buf[7] = {USB5744_CREG_MEM_ADDR, 5,
-			  USB5744_CREG_WRITE, 1,
-			  USB5744_CREG_RUNTIMEFLAGS2,
-			  USB5744_CREG_RUNTIMEFLAGS2_LSB,
-			  USB5744_CREG_BYPASS_UDC_SUSPEND};
-
-	ret = i2c_smbus_write_block_data(client, 0, sizeof(wr_buf), wr_buf);
+	ret = onboard_dev_5744_i2c_read_byte(client,
+					     USB5744_CREG_RUNTIMEFLAGS2, &reg);
 	if (ret)
-		return dev_err_probe(dev, ret, "BYPASS_UDC_SUSPEND bit configuration failed\n");
+		return dev_err_probe(dev, ret, "CREG_RUNTIMEFLAGS2 read failed\n");
 
-	ret = i2c_smbus_write_word_data(client, USB5744_CMD_CREG_ACCESS,
-					USB5744_CMD_CREG_ACCESS_LSB);
+	reg |= USB5744_CREG_BYPASS_UDC_SUSPEND;
+	ret = onboard_dev_5744_i2c_write_byte(client,
+					      USB5744_CREG_RUNTIMEFLAGS2, reg);
 	if (ret)
-		return dev_err_probe(dev, ret, "Configuration Register Access Command failed\n");
+		return dev_err_probe(dev, ret, "BYPASS_UDC_SUSPEND bit configuration failed\n");
 
 	/* Send SMBus command to boot hub. */
 	ret = i2c_smbus_write_word_data(client, USB5744_CMD_ATTACH,